2. Why is the ocean blue? 



Not all sea water is blue. Water of the Gulf Stream, off the eastern 

 coast of the United States, is a deep blue, but water of a similar current 

 off Japan is so dark that it has been named Kuroshio (Black Stream). 

 In other areas water may be various shades of green, brown, or brownish- 

 red. 



The sea is blue for the same reason that the sky is blue. The blue of 

 the sea is caused by scattering of sunlight by tiny particles suspended in 

 the water. Blue light, being of short wave length. Is scattered more ef- 

 fectively than light of longer wave lengths. 



Although waters of the open ocean are commonly some shade of 

 blue, especially in tropical or subtropical regions, green water is com- 

 monly seen near coasts. This is caused by yellow pigments being mixed 

 with blue water. Microscopic floating plants (phytoplankton) are one 

 source of the yellow pigment. Other microscopic plants may color the 

 water brown or brownish-red. Near shore silt or sediment in suspension 

 can give waters a brownish hue; outflow of large rivers can often be ob- 

 served many miles offshore by the coloration of suspended soil particles. 



The color of the sea changes constantly because of clouds passing 

 across the face of the sun or because of the angle of the sun's rays pass- 

 ing through the atmosphere. 



Oceanographers record the color of the ocean by comparison with 

 a series of bottles of colored water known as the Forel scale. 



Bowditch, Nathaniel 



American Practical Navigator, U. S. Naval Oceanographic Office, 



1958. 

 Carrington, Richard 



A Biograpfiy of the Sea, Basic Books, 1960. 

 Miller, Robert C. 



The Sea, Random House, 1966. 



